1. Field of the Invention
This invention relates to a holding structure for a long stopper used in continuous casting. The continuous casting long stopper will hereinafter be referred to as xe2x80x9clong stopper.xe2x80x9d
2. Description of the Prior Art
In the prior art, an insert screw brick t or a spindle u is conventionally used when a long stopper s is held on a holding rod r, as shown in FIGS. 7A and 7B. The screw brick t or the spindle u is screwed so that the long stopper s is connected to the holding rod r. Thereafter, a lock nut w is screwed down on the rod r to lock the long stopper s. A gap between a female screw x of the long stopper s and the screw brick t or the spindle u is filled with mortar y serving both a sealing material and a cushioning material. Furthermore, a pin z is driven into holes formed across the long stopper s and the rod r respectively as shown in FIG. 7C.
In the above-described screwed type, however, mortar adherent to an outer circumference of the screw brick t or the spindle u needs to be removed away every time the long stopper s is replaced. The removing work is troublesome and time-consuming. Furthermore, the pin z needs to be driven into and out of holes of the long stopper s and the rod r every time the long stopper is replaced. Particularly when the long stopper s is of the gas blowing type, sealing against air is rendered incomplete.
Therefore, an object of the present invention is to provide a holding structure for a continuous casting long stopper which can simplify replacement of the long stopper, provide a stable engagement between the long stopper and the holding rod, prevent disengagement during operation, and be applied to the long stopper of the gas blowing type.
The present invention provides a holding structure for a continuous casting long stopper, comprising a continuous casting long stopper including a shaft insertion hole formed in an upper end thereof, a protrusion insertion groove contiguous to and axially opposed to the shaft insertion hole, and a horizontal engagement groove contiguous to a lower end of the protrusion insertion groove, and a holding rod including a shaft inserted into the shaft insertion hole, the shaft having a lower end on which a radially protruding locking protrusion is formed. In the structure, after the shaft of the holding rod is inserted into the shaft insertion hole such that the locking protrusion reaches the protrusion insertion groove, the locking protrusion is caused to engage the engagement groove by rotation of either the shaft of the holding rod or the long stopper relative to the other.
According to the above-described structure, the shaft of the holding rod is inserted into the shaft insertion hole of the long stopper, and the locking protrusion is inserted into the protrusion insertion groove to reach its lower end. Either the shaft or the long stopper is rotated relative to the other so that the locking protrusion engages the engagement groove, whereby the long stopper is attached to the holding rod. When the long stopper is to be detached from the holding rod, either the shaft or the long stopper is rotated relative to the other so that the locking protrusion disengages from the engagement groove. Consequently, since the long stopper is attached to and detached from the holding rod with ease, the long stopper can easily be replaced by a new one.
In a preferred form, the holding rod includes a flange fixed thereto, the long stopper has an upper end face, and the holding rod is provided with a coil spring disposed between the flange and the upper end face of the long stopper. Consequently, an axially urging force of the coil spring can firmly engage the locking protrusion with the engagement groove.
In another preferred form, the holding rod includes a ring fitted with the shaft thereof and having a detent pin mounted thereon so as to extend axially with respect to the holding rod. Furthermore, the flange has a detent pin insertion hole which is in alignment with the protrusion insertion groove of the long stopper when the locking protrusion of the holding rod is in engagement with the engagement groove of the long stopper. Additionally, the detent pin has a lower end inserted into the protrusion insertion groove of the long stopper. In this structure, the lower end of the detent pin is inserted into the insertion groove of the long stopper so that rotation of the holding rod is prevented. Consequently, even when the long stopper is repeatedly subjected to an axial shock or impact during operation, the rotation of either the rod or the long stopper relative to the other can be prevented, whereupon the engagement protrusion can be prevented from disengaging from the engagement groove.
In further another preferred form, the long stopper has a stopper head formed with a through hole through which a gas is caused to blow out of the stopper head. Consequently, the holding structure can be applied to long stoppers of the inert gas blowing type.